I do not plan to use my common orbs or common trading essences. It would be cool if there was a crucible I could, say, throw 300 common orbs and some gold into it and get 100 rare orbs out. Likewise with essences, convert 100 common into 25 rare or whatever.

The design of the orb cruclble could be such that what comes out is based on what goes in: So, if you put in nothing but earth and flame orbs, you get granite or aztec orbs back, etc.